全文获取类型
收费全文 | 24725篇 |
免费 | 5912篇 |
国内免费 | 144篇 |
专业分类
耳鼻咽喉 | 650篇 |
儿科学 | 760篇 |
妇产科学 | 782篇 |
基础医学 | 829篇 |
口腔科学 | 2715篇 |
临床医学 | 4553篇 |
内科学 | 5856篇 |
皮肤病学 | 531篇 |
神经病学 | 2139篇 |
特种医学 | 1084篇 |
外科学 | 4124篇 |
综合类 | 69篇 |
现状与发展 | 12篇 |
一般理论 | 3篇 |
预防医学 | 2975篇 |
眼科学 | 372篇 |
药学 | 448篇 |
中国医学 | 14篇 |
肿瘤学 | 2865篇 |
出版年
2024年 | 169篇 |
2023年 | 1129篇 |
2022年 | 413篇 |
2021年 | 756篇 |
2020年 | 1289篇 |
2019年 | 575篇 |
2018年 | 1415篇 |
2017年 | 1349篇 |
2016年 | 1606篇 |
2015年 | 1659篇 |
2014年 | 2073篇 |
2013年 | 2534篇 |
2012年 | 993篇 |
2011年 | 961篇 |
2010年 | 1482篇 |
2009年 | 2040篇 |
2008年 | 928篇 |
2007年 | 694篇 |
2006年 | 831篇 |
2005年 | 634篇 |
2004年 | 477篇 |
2003年 | 429篇 |
2002年 | 401篇 |
2001年 | 443篇 |
2000年 | 323篇 |
1999年 | 435篇 |
1998年 | 536篇 |
1997年 | 508篇 |
1996年 | 548篇 |
1995年 | 401篇 |
1994年 | 322篇 |
1993年 | 267篇 |
1992年 | 210篇 |
1991年 | 184篇 |
1990年 | 164篇 |
1989年 | 165篇 |
1988年 | 151篇 |
1987年 | 140篇 |
1986年 | 122篇 |
1985年 | 111篇 |
1984年 | 96篇 |
1983年 | 109篇 |
1982年 | 97篇 |
1981年 | 77篇 |
1980年 | 53篇 |
1979年 | 50篇 |
1978年 | 44篇 |
1977年 | 54篇 |
1976年 | 41篇 |
1975年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Jeffrey T Cope MD Michael C Mauney MD David Banks BS Oliver A.R Binns MD Christopher L Moore BS Jeffrey J Rentz BS Kimberly S Shockey MS R.Christoper King MD Irving L Kron MD Curtis G Tribble MD 《The Annals of thoracic surgery》1997,63(6)
Background. Hypoxia and warm ischemia produce severe injury to cardiac grafts harvested from non–heart-beating donors. To potentially improve recovery of such grafts, we studied the effects of intravenous phenylephrine preconditioning.Methods. Thirty-seven blood-perfused rabbit hearts were studied. Three groups of non–heart-beating donors underwent intravenous treatment with phenylephrine at 12.5 (n = 8), 25 (n = 7), or 50 μg/kg (n = 7) before initiation of apnea. Non–heart-beating controls (n = 8) received saline vehicle. Hypoxic cardiac arrest occurred after 6 to 12 minutes of apnea, followed by 20 minutes of warm in vivo ischemia. A 45-minute period of ex vivo reperfusion ensued. Nonischemic controls (n = 7) were perfused without antecedent hypoxia or ischemia.Results. Phenylephrine 25 μg/kg significantly delayed the onset of hypoxic cardiac arrest compared with saline controls (9.6 ± 0.5 versus 7.7 ± 0.4 minutes; p = 0.00001), yet improved recovery of left ventricular developed pressure compared with saline controls (57.1 ± 5.3 versus 41.0 ± 3.4 mm Hg; p = 0.04). Phenylephrine 25 μg/kg also yielded a trend toward less myocardial edema than saline vehicle (p = 0.09).Conclusions. Functional recovery of nonbeating cardiac grafts is improved by preconditioning. We provide evidence that the myocardium can be preconditioned with phenylephrine against hypoxic cardiac arrest.(Ann Thorac Surg 1997;63:1664–8) 相似文献
102.
103.
104.
105.
106.
107.
108.
RATIONALE AND OBJECTIVES. The sialographic ductal patterns of the parotid glands in patients with Sj?gren syndrome were compared with those of normal patients by measuring the fractal dimensions. METHODS. Fractal dimensions were estimated using the modified pixel dilation method. RESULTS. The mean fractal dimension was 1.64 +/- 0.06 for the normal glands and 1.39 +/- 0.10 for the glands with Sj?gren syndrome (P < .005). No correlation between the age or sex and fractal dimension was observed for both groups. In Sj?gren syndrome, a significant difference in the fractal dimension was observed between the subgroup having punctuate fillings with a diameter less than 1 mm and the subgroup from 1 to 2 mm (P < .001). CONCLUSION. The fractal dimension is useful as a numeric grading of the complexity of the ductal pattern and the progression of parotid disease. 相似文献
109.
Evidence of Increased Class I MHC Expression on Human Peripheral Blood Lymphocytes during Acute Ethanol Intoxication 总被引:1,自引:0,他引:1
Michael A. Kolber PhD MD Ron M. Walls MD Marion L. Hinners MS Dinah S. Singer PhD 《Alcoholism, clinical and experimental research》1988,12(6):820-823
Certain ethanol-related diseases in humans have been linked to disorders of immunity. Although humoral and cellular immunity have been studied, the precise mechanisms whereby ethanol use leads to tissue damage remain unknown. In order to explore the hypothesis that ethanol may lead to alteration in expression of tissue Class I major histocompatibility antigen causing an autoimmune phenomenon, a population of acutely ethanol-intoxicated patients was studied. Measurement of Class I major histocompatibility antigen on peripheral blood lymphocytes in this population showed a highly significant (p less than 0.01) increase over controls. The role that this increased antigenicity may play in the evolution of clinical disease is discussed. 相似文献
110.